สุรางค์รัตน์ ถือทอง. Physical Properties and Quality Changes During Microwave Vacuum Drying of Shrimp. Master's Degree(Food Engineering). King Mongkut's University of Technology Thonburi. : King Mongkut's University of Technology Thonburi, 2006.
Physical Properties and Quality Changes During Microwave Vacuum Drying of Shrimp
Abstract:
The goals of this study were to investigate the use of microwave vacuum system to produce dried shrimp and to study the changes of physical properties of vacuum dried shrimp as
affected by the drying parameters. A prototype equipment was constructed using a 2.45 GHz commercial inverter microwave oven equipped with a vacuum chamber and connected
to a 1 hp vacuum pump operating at 3 kPa. Fresh shrimps 35-40 ct were obtained from local markets and cooked at 100ํC for 1.5 minutes in 2-3 percent brine solution. The sequence
of drying treatments (vacuum evaporation and dielectric heating) was alternated to observe the effects of drying conditions on the final quality of the dried product. The physical
properties of the microwave vacuum (MV) dried product were superior to those of hot air and sun dried shrimps in terms of toughness, redness, browning index, shrinkage and
rehydration properties. Using 157.1W of estimated microwave heating on the shrimp sample for 7 minutes, the MV dried shrimps were able to achieve the final moisture content of
22% (w.b.) surpassing the average value of the sun-dried products (approximately 25 percent). When comparing to the hot air dried shrimps, the MV dried product was larger in size
(less shrinkage). The external appearance was redder and less browned than the hot air dried shrimp as a result of only mild thermal exposure and fast processing in the absence of
oxidation. After rehydration, the sample was able to retain the shape, color and desirable quality of the fresh cooked shrimp.